Probability Question(s)

(I knew I shouldive stayed awake in statistics class)

Let's say your school was holding a lottery, and the winner would recieve $100. The chances of winning the lottery with 1 ticket is only 1/50, BUT: What are the odds of winning if you use like 20 tickets?

>>6
http://en.wikipedia.org/wiki/Hypergeometric_distribution

This especially: http://upload.wikimedia.org/math/d/9/0/d900c57f61cf66ee1be517471f915c8c.png
D = winning tickets
N = number of tickets (50*D in this case)
n = tickets bought
k = desired number of wins
Eg. if there are 2 winning tickets, you need to evaluate the formula for both k=1 and k=2 and sum those two results (since you don't care whether you only win one or both prizes).